Crank driven mechanism



Feb. 19, 1935. N KNAUS 1,991,945

' CRANK DRIVEN MECHANISM Filed May 22, 1954 2 Sheets-Sheet 1 Feb. 19, 1935. KNAU 1,991,945

CRANK DRIVEN MECHANISM I Filed May 22, 1934 2 Sheets-Sheet 2 v jl 'z'cholauc Knaus Patented Feb. 19, 1935 UNITED STATES 1,991,945 CRANK DRIVEN MECHANISM Nicholaus Knaus, Newark, N. J assignor to The 1 Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application May 22,1934, semi No. 726,949 3 Claims. (01. 74 40) This invention relates to crank-driven mechanisms, more particularly'of the ball-and-socketed crank-and-pitman type commonly used in sewing machines, and hasfor an object to provide a ball-crank and pitman mechanism which.

may be manufactured without expensive lapping operations and the parts of which are readily replaceable at minimum expense. Afurther object of the invention is to provide a ball-crank and pitman mechanism having improved-wearing qualities. Still further, the invention has for an object to providev aball-crank and pitman mechanism with simplified and improved means for steadying the pitman against lateral wabbling about its longitudinal axis. I

. With the above'and ther objects in view, as will hereinafter appear, the invention comprises the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings, from which the several features of the invention and the. advantages attained thereby will be readily understood by those skilled in the art.

In the drawings-Fig.- 1 is a front elevation of a sewing machine embodying the invention. Fig. 2 is a sectional view of the crank-and-pitman mechanism at the. free end of the main shaft of the machine shown in Fig.1. Fig. 3 is a section on the line 3, 3, Fig. 1. Fig. 4 is a section onthe line 4-4, Fig. 1; Fig. 5 is a perspective view of the split ball shown in Fig. 4. Fig. 6 is an end elevation of the same ball before it is split into two pieces. Fig. 7 is a fragmentary left end elevation of the machine shown in Fig. 1, and Fig. 8 is a disassembled perspective view of the crankand-pitman mechanism of Figs. 2 and 3.

The invention is shown as embodied in a sewing machine having substantially the constructive features disclosed in the Grieb et al. Patent No. 1,888,799, of Nov. 22, 1932. Such a machine has a frame including a bed 1 and overhanging bracket-arm 2 terminating in the head 3 in which reciprocates the needle-bar 4 carrying the needle 5. Journaled in the bushings 6 and 7, in the bracket arm 2 and bed-pedestal 8, respectively, is the main-shaft 9 formed between its ends with the needle-bar-actuating cylindrical crank 10 and having secured to its free end the crank-head 11 in which is fixed the cylindrical crank-pin l2.

The crank 10 has a cylindrical outer bearing surface and is embraced by the two-halves 13, 13' of a split bushing having an inner cylindrical bearing surface 14 and anouter spherical hearing surface 15. The bushing 13, 13' is preferably made initially in one piece, as shown in Fig. 6, with the shallow internal diametrically opposed grooves 16 and the deep external grooves 17in the plane of the internal grooves 16, providing thethin parting wal1s18 which'hold the two 5 halves of the bushing together as one piece while it. is being hardened andground to size, after which it is split apart in the plane of the grooves 16, 17 and assembled on the crank 10. The bushing 13, 13' is'embraced by the lowe strapped and spherically socketed end of a pitman 19, the upper strapped and spherically socketed end of which embraces the ball 20 on the driven element or needle-banactuating lever 21 fulcrumed at 22 in the bracket-arm 2 and connected by the usual link 23 to the needle-bar 4. To prevent relative" rotation of the spherically surfaced bushing 13, 13' andthe pitman 19, and to steady the pitman 19 against wabbling about its longitudinal axis, the upper section 13 of the bushing is provided externally with a radial keyslot 24. the sidewalls of which are parallel to one another and to the axis of thecylindrical crank 10. The lower spherically socketed end of the pitman 19 is provided internally with a key-slot 25 the side walls of which are parallel to one another and to the axis of the crank 10 and are spaced apart the same distance as the side-walls of the-slot 24. A key disk 26 is disposed in the registering-slots 24, 25. The key 26 permits the pitman 19 to tilt to a limited extent upon the bushing 13, 13 in planes parallel to the axis of the cylindrical crank 10 but prevents wabbling of the pitman on its own longitudinal axis.

There being but a slight rocking or tilting motion of the pitman 19 on the bushing 13, 13'.

and no rotation of the bushing relative to the pitman, but little wear will occur upon the spherical bearing surfaces which do not have to be so carefully fitted and lapped together as where the ball turns in the pitman socket. The cylindrical bearing surfaces of the crank 10 and bushing 13 which receive the wear of rotation of the crank are readily ground accurately to size and are of greater axial length and less diameter than the spherical bearing surfaces. This is conducive to longer life of the parts.

The crank-pin 12 at the free end of the mainshaft 9 has removably secured to it an inner cylindrical bushing 27 having at its inner end a keyslot 28, Fig. 8, which engages the key-pin 29 at the base of the crank-pin 12. The inner bushing 27 is held rigidly in place on the crank-pin 12 by means of the washer 30 and nut 31 and constitutes a removable and replaceable crank- 55 7 element having an outer cylindrical bearing surface 32.

J ournaled on the inner bushing 27 is the outer bushing 33 having an inner cylindrical bearing surface 34 and an outer spherical bearing surface 35 embraced by the upper strapped and spherical- 1y socketed end of a pitman 36 the lower strapped and spherically socketed end of which embraces the ball 37 on the driven element or overedge looper-lever 38 fulcrumed on the stationary crossshaft 39. Relative rotation of the outer bushing 33 and pitman 36 is prevented by means of a key disk 40 similar to the key disk 26 previously described. This key fits between the parallel side walls of the registering slots 41 and 42 in the ball surfaced bushing 33 and pitman 36, respectively, and prevents Wabbling of the pitman 36 on its own longitudinal axis;

The looper-lever 38 carries the usual over-edge implement 43 and has an arm 44 which is connected by means of the spaced parallel links 45 to the usual carrier-lever 46 for the looper 47, fulcrumed on the stud-shaft 46'.

It will be observed that the crank 12 has an oil-duct 48 therein leading from the undercut oil catching groove 49 overhanging one end of the main-shaft bearing bushing '7. The oil-duct 48 centrifugally discharges oil through the radial outlet 50 to the crank bearing surfaces 32 and 34. Oil also passes downwardly through the opening 51, Fig. 3, into the slot 41 and around the peripheral groove 52 in the key disk 40 to the duct 53 in the pitman 36 leading to the ball 37.

Similarly, oil from the bearing bushing 6 is caught by the undercut groove 54 and is fed centrifugally through the duct 55 to the bearing surfaces of the bushing 13, 13. Oil is also fed centrifugally upwardly through the duct 56 and around the peripheral groove 57, Fig. 4, in the key disk 26 to the duct 58 in the pitman 19, which duct leads the oil to the ball 20.

The main-shaft bearings 6 and '7 are lubricated by wicks 59, 60, respectively, which lead upwardly to said bearings from the oil-cavity 61 in the bed 1. The bearing studs 39 and 46 for the overedge implement carrier 38 and loopercarrier 46 are similarly lubricated by wicks 62 and 63, respectively. The bearings at the ends of the links 45 are lubricated through oil-ducts 64, 65 in the arms 44 and 46, respectively, which at their lower ends pick up oil by centrifugal action from the bearings 39 and 46'. tem of lubrication is, in general, substantially in accordance with the disclosure of the U. S. patent to Grieb et al., No. 1,888,799, previously referred to.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a crank-driven mechanism, a driveshaft having a cylindrical crank-element, a ballmember removably embracing said crank-element, a pitman element removably embracing said ballmember, and a driven member connected to be actuated by said pitman element, the ball-member and pitman element having registering slots in their proximate spherical bearing surfaces atfording spaced parallel side walls which are parallel to the axis of said crank, and a key having parallel side faces received in said registering slots.

2. In a crank-driven mechanism, a drive-shaft having a cylindrical crank-element, a ball-member removably embracing said crank-element, a pitman element removably embracing said ball-' member, and a driven member connected to be actuated by said pitman element, the ball-member and pitman element having registering slots cut in their proximate spherical bearing surfaces affording spaced parallel side walls which are parallel to the axis of said crank, and a key disk having parallel side faces received in said registering slots.

3. In a crank-driven mechanism, a drive-shaft having a cylindrical crank-element, a ball-member removably embracing said crank-element, a pitman element removably embracing said ballmember, and a driven member connected to be actuated by said pitman element, the ball-member and pitman element having, registering 'slots cut intheir proximate spherical bearing surfaces affording spaced parallel side walls which are parallel to the axis of said crank, a key disk having parallel side faces received in said registering slots and a peripheral oil-groove, said crank having an internal oil-duct leading to one of said slots and said pitman having an oil-duct leading from the other of said slots to said driven element.

NICHOLAUS KNAUS.

This sys-' 

